聚对二氧环己酮/聚乙二醇多嵌段共聚物的合成与表征

首先合成双端羟基的聚对二氧环己酮预聚物(PPDO)和双端羧基的聚乙二醇预聚物(PEG),然后以丁二酸酐/二环己基碳二亚胺(DCC)将PPDO与PEG偶联共聚,得到PPDO/PEG多嵌段共聚物.通过1H-NMR和GPC表征了聚合物的结构和分子量.采用差示扫描量热法(DSC)和热重分析(TGA)研究了共聚物的结晶性能和热稳定性.用透析法制备了共聚物纳米粒子,并用动态光散射(DLS)表征了共聚物纳米粒子的粒径及分散度,结果表明,随着共聚物亲水链段PEG含量的增加,其纳米粒子更易形成,粒子粒径随共聚物分子量增大而增大.     

丙烯酸接枝邻苯二酚衍生物的二次聚合

合成了2种聚合前驱体邻苯二丙烯酸酯(o-PDA)和2-甲氧基苯丙烯酸酯(2-MOPA), 分别通过与丙烯酸(AA)自由基共聚得到邻苯二丙烯酸酯-丙烯酸共聚物(O1)和2-甲氧基苯丙烯酸酯-丙烯酸共聚物(O2). 产物邻苯二酚(o-DHB)-O1(质量比1∶1)和1-羟基-2-甲氧基苯(HMOB)-O2(质量比1∶1)分别在乙腈/二氯甲烷-三氟化硼乙醚体系中直接阳极氧化聚合获得交联网状共聚物P1和P2. P1和P2均可溶于DMSO, 而难溶于ACN, DCM和THF等有机溶剂. 通过UV-Vis, FTIR和 ¹H NMR对交联共聚物膜的结构进行了表征. AA的引入不仅可以增加链的柔韧性, 而且提高了共聚物的力学性能. 而o-DHB/ HMOB的引入极大地减弱了单体的聚合位阻, 实现了单体的二次聚合, 同时也增强了单体及聚合物的电化学活性. 荧光光谱显示, 得到的2种交联共聚物膜分别在415和487 nm处有较强的发射峰, 表明共聚物仍具有良好的蓝色发光性能, 且聚丙烯酸结构的引入并没有对聚邻苯二酚(Po-DHB)和聚(1-羟基-2-甲氧基苯)(PHMOB)产生较大的荧光猝灭作用. 热重分析曲线(TGA)表明2种交联共聚物膜均具有较高的热稳定性.     

苯胺四聚体-聚乙二醇-苯胺四聚体嵌段共聚物薄膜的自组装

以氨基封端的苯胺四聚体为基础,以甲苯2,4-二异氰酸酯(TDI)为中间体制备了苯胺四聚体-聚乙二醇-苯胺四聚体(ANI₄-PEG-ANI₄,PEG600,M_n＝600)嵌段共聚物,并溶于乙醇/N,N-二甲基甲酰胺(DMF)混合溶剂后,涂覆于导电玻璃(ITO)表面制备成薄膜,利用原子力显微镜(AFM)、紫外-可见光谱(UV-Vis)和循环伏安(CV)等研究了薄膜的自组装及电化学行为等,讨论了诱导溶剂对嵌段共聚物薄膜形态和性能的影响. 研究发现,通过改变混合溶剂比和诱导溶剂种类,ANI₄-PEG-ANI₄嵌段共聚物薄膜可以实现多种形态的转变.     

锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究Ⅱ锆螯合物与丙烯酸酯三元共聚物无皂水溶胶的交联反应

研究了三元丙烯酸酯共聚物(MMA/BA/AA)无皂水溶胶中加入三乙醇胺锆螯合物对水溶胶及涂膜性能的影响. 在水溶胶中,螯合物增加了共聚物的亲水性,改变了水溶胶的流变性、稳定性、表面张力. 螯合物也提高了共聚物涂膜的耐水性. X光电子能谱(XPS)研究表明,在固化成膜过程中螯合物与共聚物发生交联反应,用IR、1H NMR、DSC、TGA和UV等分析方法对其交联机理作了初步探讨.     

聚对二氧环己酮/聚乙二醇两亲性聚合物共网络的合成与表征

以辛酸亚锡为催化剂,季戊四醇(PTOL)为引发剂,引发对二氧环己酮(PDO)单体开环聚合,合成了以PTOL为核的四臂聚对二氧环己酮(4s-PPDO).通过直接将4s-PPDO预聚物和聚乙二醇(PEG)于熔点以上、惰性气体保护下与偶联剂甲苯二异氰酸酯(TDI)交联共聚得到聚对二氧环己酮/聚乙二醇(PPDO-b-PEG)两亲性共网络聚合物(PPDO-PEG APCNs).研究了两亲性聚合物共网络结构、配比组成、溶剂种类等对聚合物溶胀率的影响,结果表明APCNs在不同类型的溶剂中表现出不同的溶胀行为,可以通过调节偶联剂的用量及PPDO/PEG的投料比来满足不同的实际需求.通过示差扫描量热分析(DSC)详细研究APCNs的结晶性能,证实交联反应降低APCNs的结晶度和结晶尺寸.     

在交联聚合物微球GMA/MMA表面接枝固载聚乙二醇的研究

以乙二醇二甲基丙烯酸酯为交联剂,采用悬浮聚合方法,制备了甲基丙烯酸缩水甘油酯(GMA)和甲基丙烯酸甲酯(MMA)的交联微球GMA/MMA.使用Lewis酸催化剂,通过环氧键的开环反应,将聚乙二醇(PEG)偶合接枝在交联微球GMA/MMA表面,实现了PEG的固载化,制得了三相相转移催化剂PEG-GMA/MMA.重点考察了各种因素对PEG接枝固载过程的影响,并研究了反应机理.实验结果表明,以交联微球GMA/MMA为载体,可以顺利地实现PEG的固载化,这是制备PEG三相相转移催化剂的简捷途径.实验发现,Lewis酸也能催化环氧键的开环反应,而且比质子酸的催化更加有效.溶剂的极性对偶合接枝反应的影响较大,采用极性大的溶剂有利于PEG的接枝固载.偶合接枝体系中,过高的催化剂用量会导致PEG双端羟基参与接枝反应,使载体表面大分子之间发生附加交联,不利于PEG的接枝固载.在适宜的反应条件下,接枝微球PEG-GMA/MMA表面的PEG接枝度可达0.20 g/g.     

pH响应性聚氨酯薄膜的制备

聚氨酯基水凝胶是一种重要的生物医学材料[1 ] ,文献中已报道了块状聚氨酯水凝胶[2 ,3] 、聚氨酯与聚丙烯酸酯的互穿网络水凝胶[4] 、温度及 pH双敏性聚氨酯基水凝胶[5] 等 ,但有关薄膜状聚氨酯凝胶材料还未见报道。本文合成了 5个端丙烯酸酯基聚氨酯预聚物 ,通过紫外光照射固化 ,得到了具有快速pH响应性的敏感薄膜。端丙烯酸酯基聚氨酯预聚物乳液 (PU)参照 [5 ]方法合成。固定聚乙二醇 (PEG)与 2 ,2 二羟甲基丙酸 (DMPA)摩尔比为 3∶7,先使全部的 1 ,6 六亚甲基二异氰酸酯 (HMDI)与PEG及DMPA反应制得异氰酸酯封端的预聚物 ,将该…     

含氟丙烯酸酯-苯乙烯共聚物的制备及其表面性能的研究

研究了聚合工艺、含氟丙烯酸酯类单体种类和用量、苯乙烯和自由基引发剂用量及硅烷偶联剂、催化剂等因素对含氟丙烯酸酯-乙烯共聚物表面性能的影响。结果表明：聚合工艺、含氟丙烯酸酯类单体种类和用量对共聚物表面的憎水性能有显著的影响;采用延时滴加含氟丙烯酸酯类单体可提高共聚物膜表面的憎水性;随含氟丙烯酸酯类单体侧链含氟烷基的链长和氟原子数及含氟单体用量的增加,共聚物水接触角增大,吸水率下降;共聚物薄膜的硬度则与含氟丙烯酸酯类单体中α-取代基、侧链含氟烷基的链长和用量、苯乙烯用量、引发剂浓度等相关;硅烷偶联剂和催化交联剂的加入可提高共聚物薄膜的强度。     

锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究Ⅰ丙烯酸酯三元共聚物合成条件对无皂水溶胶性能的影响

三乙醇胺螯合锆烷氧化物;交联反应;锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究 Ⅱ锆螯合物与丙烯酸酯三元共聚物无皂水溶胶的交联反应     

锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究Ⅰ丙烯酸酯三元共聚物合成条件对无皂水溶胶性能的影响

三乙醇胺螯合锆烷氧化物;交联反应;锆螯合物交联丙烯酸酯共聚物无皂水溶胶的研究 Ⅱ锆螯合物与丙烯酸酯三元共聚物无皂水溶胶的交联反应     

Investigation of swelling and network parameters of poly(ethylene glycol)-crosslinked poly(methyl vinyl ether-co-maleic acid) hydrogels

The influence of poly(ethylene glycol) (PEG) plasticiser content and molecular weight on the physicochemical properties of films cast from aqueous blends of poly(methyl vinyl ether-co-maleic acid) was investigated using thermal analysis, swelling studies, scanning electron microscopy (SEM) and attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy. FTIR spectroscopy revealed a shift of the CO peak from 1708 to 1731 cm⁻¹, indicating that an esterification reaction had occurred upon heating, thus producing crosslinked films. Higher molecular weight PEGs (10,000 and 1000 Da, respectively), having greater chain length, producing hydrogel networks with lower crosslink densities and higher average molecular weight between two consecutive crosslinks. Accordingly, such materials exhibited higher swelling rates. Hydrogels crosslinked with a low molecular weight PEG (PEG 200) showed rigid networks with high crosslink densities and, therefore, lower swelling rates. Polymer:plasticizer ratio alteration did not yield any discernable patterns, regardless of the method of analysis. The polymer-water interaction parameter (χ) increased with increases in the crosslink density. SEM studies showed that porosity of the crosslinked films increased with increasing PEG MW, confirming what had been observed with swelling studies and thermal analysis, that the crosslink density must be decreased as the M_w of the crosslinker is increased. Hydrogels containing PMVE/MA/PEG 10,000 could be used for rapid delivery of drug, due to their low crosslink density. Moderately crosslinked PMVE/MA/PEG 1000 hydrogels or highly crosslinked PMVE/MA/PEG 200 systems could then be used in controlling the drug delivery rates. We are currently evaluating these systems, both alone and in combination, for use in sustained release drug delivery devices.     

Synthesis and characterization of poly(ethylene glycol) methyl ether endcapped poly(ethylene terephthalate)

Linear and branched poly(ethylene terephthalate) (PET) copolymers with polyethylene glycol) (PEG) methyl ether (700 or 2000 g/mol) end groups were synthesized using conventional melt polymerization. DSC analysis demonstrated that low levels of PEG end groups accelerated PET crystallization. The incorporated PEG end groups also decreased the crystallization temperature of PET dramatically, and copolymers with a high content of PEG (>17.6 wt%) were able to crystallize at room temperature. Rheological analysis demonstrated that the presence of PEG end groups effectively decreased the melt viscosities and facilitated melt processing. XPS and ATR-FTIR revealed that the PEG end groups tended to aggregate on the surface, and the surface of compression molded films containing 34.0 wt% PEG were PEG rich (85 wt% PEG). PEG end-capped PET (34.0 wt% PEG) and PET films were immersed into a fibrinogen solution (0.7 mg/mL BSA) for 72 h to investigate the propensity for protein adhesion. XPS demonstrated that the concentration of nitrogen (1.05%) on the surface of PEG endcapped PET film was statistically lower than PET (7.67%). SEM analysis was consistent with XPS results, and revealed the presence of adsorbed protein on the surface of PET films.     

Phase behavior,crystallization, and morphology in thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin and poly(ϵ‐caprolactone)

Thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin (PEG‐ER) and poly(?‐caprolactone) (PCL) were prepared via an in situ curing reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) and maleic anhydride (MAH) in the presence of PCL. The miscibility, phase behavior, crystallization, and morphology of these blends were investigated. The uncured PCL/PEGDGE blends were miscible, mainly because of the entropic contribution, as the molecular weight of PEGDGE was very low. The crystallization and melting behavior of both PCL and the poly(ethylene glycol) (PEG) segment of PEGDGE were less affected in the uncured PCL/PEGDGE blends because of the very close glass‐transition temperatures of PCL and PEGDGE. However, the cured PCL/PEG‐ER blends were immiscible and exhibited two separate glass transitions, as revealed by differential scanning calorimetry and dynamic mechanical analysis. There existed two phases in the cured PCL/PEG‐ER blends, that is, a PCL‐rich phase and a PEG‐ER crosslinked phase composed of an MAH‐cured PEGDGE network. The crystallization of PCL was slightly enhanced in the cured blends because of the phase‐separated nature; meanwhile, the PEG segment was highly restricted in the crosslinked network and was noncrystallizable in the cured blends. The phase structure and morphology of the cured PCL/PEG‐ER blends were examined with scanning electron microscopy; a variety of phase morphologies were observed that depended on the blend composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2833–2843, 2004     

Crosslinkable poly(p‐phenylenevinylene) derivative

To simplify the fabrication of multilayer light‐emitting diodes, we prepared a p‐phenylenevinylene‐based polymer capped with crosslinkable styrene through a Wittig reaction. Insoluble poly(p‐phenylenevinylene) derivative (PPVD) films were prepared by a thermal treatment. The photoluminescence and ultraviolet–visible (UV–vis) absorbance of crosslinked films and noncrosslinked films were studied. We also studied the solvent resistance of crosslinked PPV films with UV–vis absorption spectra and atomic force microscopy. Double‐layer devices using crosslinked PPVD as an emitting layer, 2‐(4‐tert‐butylphenyl)‐5‐phenyl‐1,3,4‐oxadiazole (PBD) in poly(methyl methacrylate) as an electron‐transporting layer, and calcium as a cathode were fabricated. A maximum luminance efficiency of 0.70 cd/A and a maximum brightness of 740 cd/m² at 16 V were demonstrated. A 12‐fold improvement in the luminance efficiency with respect to that of single‐layer devices was realized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2124–2129, 2004     

Gelatin/poly(aniline) composite films: Synthesis and characterization

In this work, glyoxal (Glox) - crosslinked gelatin (Gel) films have been loaded with aniline molecules, followed by their in-situ oxidative polymerization to yield Gel/poly(Ani) composite films. The films, so prepared, have been characterized by FTIR, XRD, TGA and AFM analysis. The water absorption of these films has been studied in the physiological fluid of pH 7.4 at 37°C.The dynamic water uptake data has been interpreted by various kinetic models such as power function model and Schott kinetic model. The various diffusion coefficients have also been evaluated.     

Segmented block copolymers of poly(ethylene glycol) and poly(ethylene terephthalate)

A new series of segmented copolymers were synthesized from poly(ethylene terephthalate) (PET) oligomers and poly(ethylene glycol) (PEG) by a two‐step solution polymerization reaction. PET oligomers were obtained by glycolysis depolymerization. Structural features were defined by infrared and nuclear magnetic resonance (NMR) spectroscopy. The copolymer composition was calculated via ¹H NMR spectroscopy. The content of soft PEG segments was higher than that of hard PET segments. A single glass‐transition temperature was detected for all the synthesized segmented copolymers. This observation was found to be independent of the initial PET‐to‐PEG molar ratio. The molar masses of the copolymers were determined by gel permeation chromatography (GPC). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4448–4457, 2004     

Nonisothermal crystallization and melting behavior of the copolymer derived from p-dioxanone and poly(ethylene glycol)

Nonisothermal crystallization and melting behaviors of poly(p-dioxanone)(PPDO)-b-poly(ethylene glycol)(PEG) with mole ratios of 80:20 and 30:70, has been studied by differential scanning calorimeter using various cooling rates. Crystallization behavior of each crystallizable segments of the copolymer was compared with the corresponding segment of homopolymer. For a given composition, the crystallization process began at higher temperature when the slower scanning rates were used. The kinetics of the PPDO segments and the PEG segments in the copolymers under nonisothermal crystallization conditions were analyzed by Ozawa equation and also the crystallization results of the copolymer segments were compared with the corresponding homopolymers. The results showed that the Ozawa equation fails to describe the whole crystallization process of the copolymer segments along with PPDO homopolymer, but describes the crystallization behavior of the PEG homopolymer. Crystallization activation energy and absolute crystallinity values were estimated from the cooling scans (using Kissinger’s method) and fusion endotherms of the subsequent heating scans, respectively.     

Synthesis and characterization of novel degradable photocrosslinked poly(ether‐anhydride) networks

New degradable poly(ether‐anhydride) networks were synthesized by UV photopolymerization. Dicarboxylated poly(ethylene glycol) (PEG) or poly(tetramethylene glycol) (PTMG) was reacted with an excess of methacrylic anhydride to form dimethacrylated macromers containing anhydride linkages. The percent of conversion for the macromer formation was more than 80% at 60 °C after 24 h. ¹H NMR and IR spectroscopies show the presence of anhydride linkages in the macromer. In vitro degradation studies were carried out at 37 °C in PBS with crosslinked polymer networks formed by UV irradiation. All PEG‐based polymers degraded within 2 days, while PTMG‐based polymers degraded by 50% of the initial weight after 14 days. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1277–1282, 2000